Method for determining the neutron flux by using a portable radionuclide identification device (RID) comprising scintillation material with iodine

A method for determining neutron flux by utilizing a portable Radionuclide Identification Device (RID) wherein the RID comprises an inorganic crystal, a light detector and electronics adapted to evaluate the output signals of the light detector, the method comprising:

• detecting light emitted by the crystal based on events that comprise radiation induced interactions with the crystal using the light detector, wherein the light detector measures an intensity of the light as a function of energy deposed in the crystal by said events;
• determining the energy deposed in the crystal by evaluating a pulse height of the output signal of the light detector;
• selecting a first group of said events in a first energy window, wherein the first energy window comprises events having energies that exceed a minimum first threshold energy, ET1;
• selecting a second group of said events in a second energy window, W(n,μ),
• wherein the second energy window comprises events having energies above a second threshold energy, ET2, and below a third threshold energy, ET3, and wherein ET3 is less than or equal to ET1;
• determining a count rate R(μ) of the first group of said events,
• determining a count rate R(n,μ) of the second group of said events,
• determining, for each measurement for determining neutron flux, a background count rate R(back) from an expected count rate R(μ)exp of interactions of the cosmic radiation with the crystal in the second energy window W n,μ), wherein said expected count rate R(μ)exp is being calculated from the count rate R(μ) and a known energy distribution of cosmic radiation;
• and
• determining a neutron flux count rate R(n) by subtracting the background count rate R(back) from the count rate R(n,μ).